Acorn tube socket



June 1, 1943. w.- s. KEITH 2,320,871

ACORN TUBE SOCKET Filed June 13, 1941 INVENTOR Patented June 1, 1943ACORN TUBE SGCKET Walter S. Keith, Long. Island City, N. Y., assignor toThe Hammarlund Manufacturing Company, Incorporated, New York, N. Y., acorporation of New York Application June 13, 1941, Serial No. 397,862

4 Claims.

This invention relates to sockets for the reception of a plug or tubeprovided with radially extending contact pins.

More particularly this invention relates to a socket for the support andconnection of an electronic tube of the socalled acorn or ultra highfrequency type.

For the employment of these tubes it is necessary that a socket affordnot only a positive contact with the pins of the tube but also it isnecessary that this contact be made at a comparatively sharply definedpoint so as to aiford a current path of unchanging length, as Well asproviding comparatively low and constant eiTective capacity between thevarious contact structures. Likewise it is desirable that a socketforthis purpose include means for automatically centering the tube, inorder that an interchange of tubes will not result in a change of theefiective length of the current path through the contacts and thecontact pins.

Electronic tubes of the ultra high frequency type are usually providedwith a peripheral ringlike structiu'e in lieu of the usual base. Thisstructure is usually situated at a point intermediate the ends of thetube and projecting therethrough are a plurality of radially disposedcontact pins of relatively small diameter. These pins may be held inposition by the peripheral ring through which they project, thusavoiding the use of any insulating material other than the glass ofwhich the tube itself is composed. Such pins are comparatively rigid andnot easily bent out of the single plane in which they lie.

One form of socket which has been employed for the reception of an acorntube consists of an annular ring of insulating material having suitablehigh resistance, low dielectric constant and low surface leakage. Aroundthe periphery of this ring are locateda number of contacts, alsoradially disposed, provided toward their inner ends with some clampingdevice into which the contact pins of the tube may enter and be held.

The sockets hitherto employed have been subject to several difficultiesand defects. In general, the contact pin has made connection with thesocket contact along a path of relatively great magnitude in a radialdirection. It is to be understood that when dealing with ultra highfrequency currents, a length of current path amounting to only a fewmillimetersmay make an enormous difference in respect to the impedancepresented to such currents and may cause undesirable alterations attheseextremely high frequencies. Consequently, with sockets of the type justdescribed, the exact point at which the current passes from the tube pinto the socket contact is not a clearly defined one and accordingly thelength of the current path may vary to a degree limitedonly bythe radiallength of such contact making elements. dilficulty encountered withsockets of this type is that the contact pin of the tube not onlytouches the socket contact portions designed to receive it, but alsomakes more or less imperfect contact with the base of the socketContact; or with some other portion of the contact, thus giving rise tofurther trouble with regard to the length of'current' path.

One object of this invention is to provide a socket of the characterdescribed which will be lighter and contain less solid dielectric thansockets hitherto used and Whichtherefore will be cheaper to manufacture.

Another object of this invention is to provide a socket into which thetube prongs will snap and be firmly held so that the socket ma y bemounted in any desired position,- even inverted without danger that thetube prongs will become loosened or the tube fall out of the socket, asmay occur especially when the structure is subjected' to vibration.

Another object of thisi-nvention is to provide a socket inwhich thetotal length of the current path from the conductor to the tubeprong-when the tube is mountedin-thesocket; will be' substantiallyreduced in length and will be maintained at a constant and comparativelysharply defined value.

Another object of this invention is to provide a socket in which theinter-contact capacity will be constant and comparatively low.

Yet another purpose of this invention is to provide a socket contactwhich will engage the tube prong in such fashion" asrtocut through anysurfaceoxide or dirt which maybe present upon the prong and thus willgive rise to a contact of low effective impedance.

A further purpose of this invention is to provide means whereby an acorntube socket will receive and make good-contact with the" tube pins eventhough such pins: be somewhat bent out of a strictly r'adial position:

A still further purpose of the: invention is to provide a socket inwhich the tube con-tact pin will make connection with the socket contactonly over'a portionzof a single comparativelynar row" planesitu'ated atright anglesto the' radial directionin which this pin extends; thuskeeping the to'tal' impedance between theconductor at- Arlespecialtached to the socket and the tube pin constant to a very highdegree.

Yet another object of this invention is to provide a socket wherein thecontact between the tube pin and the socket contact member will be ofextremely low and constant ohmic resistance.

In the drawing Fig. 1 is a plan view showing a conventional acorn tubemounted in the socket of this invention.

Fig. 2 is a side elevation partly in section of the structures of Fig. 1along the line 2-2.

Fig. 3 is a view in elevation of the inner end of a single contact withthe tube prong in position, the dotted lines indicating the contactbefore entry of the prong.

Fig. 4 is a perspective view of the contact.

Fig. 5 is a side elevation of the contact.

Fig. 6 is a view of the contact flattened out so as to show all portionsthereof lying in a single plane.

The tube I has a peripheral ring H from which project radially theterminal pins or. wires l2 corresponding with the various elements ofthe tube. Additional terminal pins 12' and I2" may be provided at therespective ends of the tube.

The socket has an insulating base Hi and a number of contacts Icorresponding in number and arrangement with the tube pins. Each contactis secured to the base in a suitable manner for instance by a rivet 16.The base in this case has an opening I! somewhat larger in diameter thanthe tube diameter, so that. the tube will be supported completely out ofcontact with the base of the socket.

Each contact is formed of sheet metal of suitable characteristicpreferably beryllium copper, silver plated for better surfaceconductivity, and has a foot 18 at the outer end through which thefastening device 16 is secured and a. tongue l9 at the inner endoverlapping the edge of the recess I1 and seated in groove 11' so as toprevent rotation of the contact. The contact has two, resilient sidearms 20, 20 formed integrally at 21,, 2| with the central part of thecontact. Each arm terminates in a jaw 22. These jaws project toward eachother and have a V-shaped or rounded entrance 23 adapted to receive atube pin. A notch or shoulder 24 is, formed near the inner end of one orboth of the jaws to hold the tube pin in place engaged between the jaws22, 22 but situated above the tongue 19. Foot I8 is preferably providedwith an aperture l8 near the end thereof, for the connection of a wireto the foot.

Into such contacts the tube pins can be readily and easily inserted andsecurely held in any position of the tube and socket, either horizontal,vertical or inclined and without danger of the tube working loose orfalling out. The edges of the jaws are relatively sharp so that they cutinto the surface of the tube, pins removing any oxidation or dust andthus ensuring a perfect contact engagement.

It can be seen that even though the contact pins of the tube areaccidentally bent somewhat in a direction so that they no longer lie ina single plane, yet the contacts of this socket will still gripany pinso bent at substantially a single point along its length. Likewise incase that one or. more of the pins are bent laterally to a slightdegree, as often is the case due. to manufacturing tolerances,- thecontacts of this socket can adjust themselves to-such pins'if the degreeof bending is not too great. This ability to make such compensatoryadjustment arises from the fact that the side arms of the contact,carrying the contact making jaws at their inner extremities, bend aboutthe portions 21 which act somewhat as fulcra and are located so far awayfrom the jaws that the side arms possess considerable flexing ability orlateral play, in comparison with prior art contacts where the flexingoccurs substantially at the points where the pin enters the contact. Ifthe tube pins be considerably bent out of place, the tube may assume aposition eccentric with respect to opening ll in the center of thesocket and suitable adjustments may then be made so as to secureequalization of the effective electrical length of the circuit includingthe contact and the tube pin.

It will be evident that, while there has been illustrated a socket for atube having five radial prongs, it is possible to use a greater orlesser number of contacts and to dispose them in other positionsrelative to one another in accordance with the arrangement of radialprongs on the tube to be used.

It will be noted that the contacts of the socket are positivelypositioned so that each extends in a radial direction, since the actionof the tongues l9 serves to prevent each contact from rotating about therivet 16 used to secure it to the base, and thus serves to prevent thecontacts from touching one another and to maintain a current path ofsubstantially unchanging length for each tube prong.

For shielding purposes a suitably apertured metallic plate may bearranged to cover the bottom of the socket and additional shielding suchas an outwardly projecting collar may extend from the plate along thesides of the tube passing therethrough, as well known in the art.

I claim:

1. In a socket for the reception of a tube having radially extendingprongs, a contact comprising a base portion terminating in a tongue forlooking to the socket, two longitudinally extending side wings extendingupwardly from the base portion, each bent inwardly at one extremity soas to form a pair of opposed jaws lying in a single plane, one of saidjaws having in the edge a notch with a bottom ledge substantiallyparallel to the base portion and with an outwardly tapered entranceportion, whereby said side wings flex about said base portion when saidjaws are spread apart by the insertion of a prong therebetween andwhereby the tapered entrance of said notch forces said inserted prongagainst said bottom ledge.

2. A prong receiving contact for use in high frequency circuits,including an elongated body formed in one piece of sheet metal andhaving two longitudinal slits therein so as to render said bodytrifurcated into three parallel and adjacent tinesjoined together at oneend of said body, the two outer tines thereof being bent about theirrespective points of juncture with the central tine, so as to extend inplanes lying respectively at right angles to said central tine, and soas to lie substantially parallel to-each other, said outer tines alsobeing-bent inwardly near the respective free ends thereof so' as to formcoplanar jaws for making substantially a line contact with a connectingpin inserted between said jaws, whereby said jaws by their opening causesaid outer tines to flex about the common point of juncture of the threetines.

3. A socket for tubes having a number of pins projecting outwardly froma central axis com.-.

prising an annular insulating base having an opening substantially inthe central axis thereof and contacts secured to said base around theopening in the base, each contact having a central portion mounted onthe upper surface of the base and terminating in a tongue embracing therim of the opening, longitudinally extending and laterally resilientarms on opposite sides of the central portion terminating in jaws facingtoward each other with a tapered entrance to a space between them andwith their edges extending substantially at right angles to the upperface of the base, at least one of the jaws having a notch provided witha bottom ledge extending substantially parallel to said central portionof the contact so as to hold an inserted tube pin, said jaw beingoutwardly tapered toward said notch 50 as to force said pin against theledge, said jaws being so arranged with respect to the base that thepins of a tube may be simultaneously inserted in the respective contactjaws by alining the pins with the spaces between the jaws of thecontacts and pushing the tube into the opening in the base.

4. An acorn tube socket including a substantially annular base ofinsulating material and contacts mounted radially thereupon, eachcontact including a base portion affixed to said base and two side armseach formed integrally with and flexing about said base portion at apoint near the outer end thereof, said arms being bent at their innerends so as to form a pair of prong receiving jaws lying substantially ina single plane, whereby said jaws are capable of relatively greatlateral movement due to the location of the point of fiexure of saidarms at a point relatively remote from said prong receiving jaws.

WALTER S. KEITH

